Emergency power supply unit



Dec. 27, 1966 DUNCAN EMERGENCY POWER SUPPLY UNIT Filed Sept. 24, 1965{HHIHIII l NVENTOR. 5 1 WW HZ'TORN'EYSI United States Patent Ofitice3,294,97 7 Patented Dec. 27, 1966 3,294,977 EMERGENCY POWER SUPPLY UNITEdward T. Duncan, Westport, Conn., assignor to The Maintenance Company,Inc., Long Island City, N.Y., a corporation of New York Filed Sept. 24,1963, Ser. No. 311,095 8 Claims. (Cl. 307-66) This is acontinuation-in-part of my copending United States patent applicationSerial Number 242,787, now abandoned, filed December 6, 1962 forEmergency Lighting Unit.

This invention relates to an emergency power supply unit and, moreparticularly, to such a unit especially adapted for use in elevatorcabs.

In my copending United States patent application Serial No. 222,574,filed September 10, 1962, for Emergency Lighting Unit, now Patent Number3,159,755, there is disclosed a novel circuit and mounting arrangementfor an emergency light which is actuated solely by loss of ambientillumination. Such a unit has a number of advantages, particularly inenclosed areas having a limited number of illumination sources. However,it is realized that some persons will prefer a unit actuated more conventionally by loss of power. Accordingly, the present invention isconcerned both with an unusual elevator cab mounting arrangement for anemergency lighting unit and also with a novel power supply circuitarrangement having many of the advantages of the aforementionedinvention but actuated by loss of electrical power.

One of the major disadvantages of the emergency lighting units known tothe prior art is that, in most instances, they are separate accessorieswhich are attached to the elevator cab as distinct entities.Accordingly, such units are seldom integrated into the functional anddecorative arrangements of the elevator interior but, rather, have theappearance of being afterthoughts. Furthermore, the fact that such unitsare not functionally integrated with the elevator cab means thatseparate wiring facilities must be provided for supplying power to theunits. If rechargeable batteries are used, ventilation should beprovided for the battery charging components. The units must bepositioned so as to illuminate the entire cab, which often requires theuse of unsightly goosenecks and similar contrivances. If actuation byillumination failure is desired, as disclosed in the aforementionedapplication, they must be positioned in a location which is continuallyexposed to ambient light.

Present-day elevators are commonly provided with cove lighting includingrecessed fluorescent or incandescent lamps positioned around the edgesof the elevator ceiling.

In addition, the central portion of the ceiling is usually occupied by aventilating unit containing a fa for circulating air between theelevator shaft and the cab interior. Accordingly, the mounting of anauxiliary emergency light in such an environment presents bothfunctional and decorative problems.

Another undesirable feature of prior art emergency lighting units and ofemergency power supply units in general is that they are controlled byrelays which receive their power from the building power circuit. Manyadditional problems are presented by the use of relays. For example,relays are normally energized at all times. This means that the coil iscontinually consuming power and, therefore, generating heat. This causesthe life of the relay to be shortened and the unit to become inoperativeafter a relatively short period of time. Furthermore, the fact that therelay is consuming power is an additional expense, which it would bedesirable to overcome. Finally, the use of relays means that movingmechanical parts are being relied upon to accomplish the switchingfunction. Mechanical parts are subject to wear and sticking, and aresensitive to vibration.

For the foregoing reasons, it is the primary object of this invention toprovide an improved emergency power supply unit. Other objects are toprovide such a unit which has storage batteries maintained in acontinuously charged state; which is free of relays and otherpowerconsuming elements; which is insensitive to vibration; which isfunctionally integrated into an elevator cab for providing emergencylight; which has adequate provision for cooling the circuit components;which is centrally located both for providing emergency light and forreceiving ambient illumination; Which is resistant to lamp filamentburnout; which is substantially maintenance-free; and in which acuationof an emergency light is by loss of power to an elevator cab.

The manner in which the foregoing objects are attained will be moreapparent from the following description, the appended claims, and thefigures of the attached drawing wherein:

FIG. 1 is an illustration of an emergency light unit constructed inaccordance with this invention;

FIG. 2 is an enlarged cross section of a portion of the emergency lightof this invention;

FIG. 3 is a cross section taken along the line 33 of FIG. 2; and

FIG. 4 is a diagram illustratin a novel circuit in accordance with thisinvention.

With particular reference to FIG. 1, there is illustrated in crosssection a portion of the ceiling 10 of an elevator cab. The ceiling 10includes an opening 12 which is normally centrally located within theceiling and receives therein a ventilating unit V. The ventilating unitV comprises an external cage C which may be formed of expanded metal ormay be any other type of housing which allows air-flow therethrough. Anelectric motor M operates a fan F for circulating air through theelevator cab. On the underneath side of ceiling 10 and within theelevator cab enclosure there is provided a louver L, which, asillustrated, may be of circular form consisting of a plurality ofconcentric rings 14, 16, 18 which are curved in vertical cross sectionso as to direct the air fiow outwardly and downwardly within theelevator cab. The louver L is surrounded by a mounting ring 20 which ismounted flat against the elevator cab ceiling 10. Mounted within theinnermost ring 14 there is an emergency lighting unit E which isconstructed as shown in FIGS. 2 and 3.

The emergency lighting unit E comprises a base 21 which is disc-shapedand positioned within the inner louver ring 14. The base 21 is securedto the louver assembly L by means of a screw 22 which is threaded into acentral stud 24 of the louver assembly. The remaining rings 16, 18 andthe external mounting ring 20 are secured together by means of thehorizonally extending rods 26, 28 and two similar rods 27, 29 whichextend perpendicular to rods 26, 28 and in the same plane. Mounted onbase 21 are a pair of lamp-supporting brackets 30, 32 to which areattached a supporting rim 34 securing a lamp 36 in a vertical positionfor downward illumination. Encircling the lamp 36 is a lamp housing 38having an upper edge 39 which contacts the lower dependent edge oflouver 14 around its circumference. The lamp housing 38 also includes acentral opening 40 for the extension of lamp 36 therethrough. Lamphousing 38 may be constructed of either an opaque material, such asmetal, or a transparent or tanslucent material, such as certainplastics. The use of a translucent material may be particularlydesirable when the emergency light is of the type disclosed in mypreviously referred to copending application for Emergency LightingUnit. In such a case the light-sensitive photocell for actuating theunit may be positioned within the housing but behind the translucentmaterial where it is protected from dirt and physical damage but issuitably positioned for the reception of ambient light. The remainingcircuit components of the emergency light are retained within thecompartment formed by the inner louver ring 14 and the lamp housing 38.These may be, for example, the transformer 42, the rechargeable cells441, 442, 443, and 444-, all of these cells comprising a" single battery44. The electrical terminals 46, 48 for lamp 36 are also mountedconveniently within the housing, as are the various circuit components,such as resistors, capacitors and rectifiers, which are indicated inFIGS. 2 and 3 but not specifically numbered.

A number of advantages result from the novel emergency li ht mountingdescribed above. For example, the emergency light becomes an integral,functional part of the elevator cab and also becomes incorporated intothe decor of the elevator interior. This is in sharp contrast to theseparate and distinct emergency light units which form the prior art.Furthermore, if the emergency lamp unit is of the photo-actuated type,as disclosed in the aforementioned copending patent application, the central location of the emergency unit allows it to be continually exposedto the ambient illumination of the cab.

It is also important to note that the emergency light unit is positionedin such a manner that its external housing is continually cooled by aflow of ventilating air. During normal operation with the lamp off, thisprovides cooling for the transformer and the other components whichmaintain the battery charge. During the period that the light is on, theoperative elements of the emergency lamp circuit will produce heat. Eventhough the fan may be off under these conditions, the location of theunit within the open ventilating passage in the cab roof allows anatural circulation of air to take place from the elevator cab to theelevator shaft. When power returns to the unit and to the fan motor M,rapid cooling of the emergency actuated units will then take place bythe action of the fan F.

In FIG. 4 there is illustrated an emergency lighting circuit suitablefor use with this invention which is especially adapted for actuation bypower failure. This circuit includes a rechargeable battery 44 which maybe, for example, of the nickelcadmium type. A transformer 42 including aprimary winding 47 and a tapped secondary winding 49 is arranged forenergizationfor example, from the same power supply as motor Millustrated in FIG. 1. The secondary winding 49 is in series withbattery 44 and is further in series with a solid state diode 50 and acurrent-limiting resistor 52. The orientation of diode 50 is such that,when the transformer 42 is energized from the primary side, thesecondary voltage will be greater than and in opposition to the voltagenormally produced by battery 44. In this manner, battery 44 ismaintained in a continual state of charge during the time transformer 42is energized. The tap of transformer secondary winding 49 is connectedto the cathode of a solid state controlled rectifier 54, such as asiliconcontrolled rectifier. The anode of rectifier 54 is connected inseries with the lamp 36 and the opposite side of the lamp is connectedto the positive terminal of the battery 44. A filter network including acapacitor 55 in series with the parallel combination of a diode 57 and aresistor 59 is connected across rectifier 54. Connected in parallelacross the series circuit of diode 50 and resistor 52 is a seriescircuit comprising a capacitor 56 which is characterized by a relativelyhigh 60-cycle impedance, a relatively low resistance 58, and arelatively large resistance 60. A diode 62 is connected from a pointbetween resistors 58 and 60 to the gate of the rectifier 54. Inaddition, a resistor 64 of relatively high value is connected inparallel between the gate and the cathode of the controlled rectifier54.

The operation of the circuit of FIG. 4 will now be explained byassuming, first, that alternating current is being supplied to theprimary of transformer 42. The secondary voltage rating of transformer42 is such that, under these conditions, the clockwise current flowaround the outer loop of the circuit through diode 50 and resistor 52 issufficient to maintain battery 44 in a charged condition. In oneapplication, for example, the secondary voltage rating of thetransformer is 12 volts and the battery is rated at 7.5 voltes. Diode 50acts as a half wave rectifier so that the secondary winding 49 ispolarized as shown and current flows from the positive terminal ofsecondary 49 to the positive terminal of battery 44. In one embodimentof the invention, capacitor 56 has a rating of .22 microfarads and 12volts D.C., resistor 58 is a 33 ohm resistor, and lamp 36 is a 2.1 wattlamp rated at 4.7 volts D.C. With components of these values, it has benfound that a very low value of half Wave rectified current passesthrough capacitor 56 and diode 62 to the gate of silicon-controlledrectifier 54 and out the anode of the rectifier in a reverse direction.This constitutes a small pre-heating current through the lamp 36 andbattery 44 to transformer secondary 49. This results in a great increasein the life of lamp 36. Normally, incandescent lamps have a relativelyshort life due to the fact that the thermal shock resulting from rapidheating of a cold filament results in stress and early filamentbreakage. By the circuit of this invention, however, the small currentflow maintains the filament in a warm, ready condition even though thelamp is not lighted. The visible glow within lamp 36 also serves as acheck on the operability of the unit without requiring actual operation.The value of resistance 60 is suificiently high to prevent triggering ofthe gate of the controlled rectifier 54. In the described example theresistance 60 has a value of 100,000 ohms. As a further aid in extendingthe life of lamp 36, it may be desirable to use a normal operatingvoltage in the circuit of less than its rated voltage. The filternetwork comprising elements 55, 57, and 59 serves to protect thecontrolled rectifier 54 from possible transient peaks.

When the AC. power to the primary of transformer 42 goes off, thesecondary winding 49 becomes, for all practical purposes, a normalelectrical conductor. Under these circumstances a reversal of currentand polarities takes place. Capacitor 56, becomes an open circuit to theD.C. current from battery 44. Gate current now flows through resistance60 and diode 62 to controlled rectifier 54. The rectifier is therebytriggered into the on state and current immediately begins to flow in areverse direction from the positive side of battery 44, through lamp 36,and through the rectifier 54 back to the negative terminal of thebattery. As long as the AC. current supply remains off therefore, lamp36 remains lighted.

Upon the recurrence of AC. voltage to the primary of transformer 42, thefirst negative (or reverse current) pulse toward the controlledrectifier 54 will cause the rectifier current flow to stop. The lamp 36goes off once again and the circuit completely reverts to its originalstate.

In the foregoing illustration, a two winding transformer 42 has beendescribed as a component of the circuit of the invention. However, itwill be understood that other apparatus, such as the autotransformer,may be employed. Accordingly, in the claims, a recitation of primary andsecondary windings is to be construed as meaning either separatewindings or portions of the same physical windmg.

It will be apparent that a number of advantages accrue from the novelcircuit and apparatus of this invention. It will also be apparent that anumber of variations and modifications may be made by those skilled inthe art without departing from the spirit and scope of this invention.Although the foregoing description has described the use of the circuitof the invention to provide emergency light in an elevator cab, it isnot so limited but may be equally adapted to other uses. For example,the illustrated circuit may be installed in a portable carrying case andplugged into a standard outlet. It would then be available as anemergency light in the event of power failure in factories, hospitals,schools, and other locations. In addition, the circuit may be employedin numerous capacities for responding to power failures. Its output, forexample, may be used for actuating alarms or functioning as an auxiliarypower supply to maintain powered equipment, such as clocks, in operationduring a power failure. These applications may be in addition to, or inplace of, its use as an emergency lighting circuit. Certain applicationsmay require minor modifications of circuit elements; however these canbe easily effected by one skilled in the art to which the inventionpertains. Accordingly, the foregoing description is to be construed asillustrative only, and the invention is limited only by the scope of thefollowing claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An emergency lighting apparatus for an elevator cab which comprises:a ventilator arranged to be mounted in the ceiling of said cab; anemergency lighting unit positioned within said ventilator, said unitcomprising transformer means having a primary winding connectable to analternating power source and a secondary winding including first andsecond terminals, rechargeable battery means and first diode meansconnected in electrical series relationship, said battery means beingconnected to said first terminal and said first diode means beingconnected to said second terminal to maintain said battery in a chargedcondition from said transformer means, solid state switching meansincluding an anode, a cathode, and a gate, emergency lamp meanspositioned to direct emergency light downward from said apparatus andconnected in series with said anode and cathode, the series circuitbeing connected in parallel with said battery, and a series circuitcomprising second diode means and relatively high impedance capacitormeans connected between said second terminal and the gate of said solidstate switching means.

2. An emergency power supply unit which comprises: transformer meanshaving a primary winding connectable to an alternating power source anda secondary winding including first and second terminals; rechargeablebattery means and first diode means connected in electrical seriesrelationship, said battery means being connected to said first terminaland said first diode means being connected to said second terminal tomaintain said battery in a charged condition from said transformermeans; solid state switching means including an anode, a cathode, and agate; controlled means connected in series with said anode and cathode,the series circuit being connected in parallel with said battery; and aseries circuit comprising second diode means and relatively highimpedance capacitor means connected between said second terminal and thegate of said solid state switching means.

3. The apparatus of claim 2 wherein said solid state switching means isa controlled rectifier.

4. The apparatus of claim 3 wherein one side of said series circuit ofrectifier and controlled means is connected to a tap on the secondary ofsaid transformer.

5. The apparatus of claim 4 wherein both of said firstand second diodemeans are positioned to conduct current in the same direction relativeto said second terminal.

6. The apparatus of claim 5 wherein said capacitor means dischargestoward said gate and changes polarity upon failure of the power supplyfrom said alternating power source, thereby activating said switchingmeans.

7. The apparatus of claim 2 wherein said controlled means is a lamp.

8. An emergency power supply unit which comprises: transformer meanshaving a primary winding connectable to an alternating current powersource and a secondary winding; rechargeable battery means and firstdiode means connected in electrical series relationship across saidsecondary winding to maintain said battery in a charged condition fromsaid transformer means; solid state switching means capable of beingswitched from a high impedance state to a low impedance state; controlmeans connected in series with said solid state switching means, theseries circuit being connected in parallel with said battery; and acapacitive triggering circuit connected across at least a portion ofsaid secondary winding in switching relationship to said solid stateswitching means.

References Cited by the Examiner UNITED STATES PATENTS 2,359,021 9/1944Campbell 315112 X 2,952,818 9/1960 Russell.

2,981,880 4/1961 Momberg.

3,049,642 8/ 1962 Quinn.

3,070,739 12/ 1962 Hansen.

3,114,095 12/1963 Palmer 307-66 X 3,158,799 11/1964 Kelley.

3,159,755 12/1964 Duncan 307-66 X 3,189,788 6/1965 Cady 30766 X OTHERREFERENCES Controlled Rectifier Manual, General Electric, First Edition,pages 9, 10 and 11, published March 1960.

ORIS L. RADER, Primary Examiner.

T. I. MADDEN, Assistant Examiner.

1. AN EMERGENCY LIGHTING APPARATUS FOR AN ELEVATOR CAB WHICH COMPRISES:A VENTILATOR ARRANGED TO BE MOUNTED IN THE CEILING OF SAID CAB; ANEMERGENCY LIGHTINT UNIT POSITIONED WITHIN SAID VENTILATOR, SAID UNITCOMPRISING TRANSFORMER MEANS HAVING A PRIMARY WINDING CONNECTABLE TO ANALTERNATING POWER SOURCE AND A SECONDARY WINDING INCLUDING FIRST ANDSECOND TERMINALS, RECHARGEABLE BATTERY MEANS AND FIRST DIODE MEANSCONNECTED IN ELECTRICAL SERIES RELATIONSHIP, SAID BATTERY MEANS BEINGCONNECTED TO SAID FIRST TERMINAL AND SAID FIRST DIODE MEANS BEINGCONNECTED TO SAID SECOND TERMINAL TO MAINTAIN SAID BATTERY IN A CHARGEDCONDITION FROM SAID TRANSFORMER MEANS, SOLID STATE SWITCHING MEANSINCLUDING AN ANODE, A CATHODE, AND A GATE, EMERGENCY LAMP MEANSPOSITIONED TO DIRECT EMERGENCY LIGHT DOWNWARD FROM SAID APPARATUS ANDCONNECTED IN SERIES WITH SAID ANODE AND CATHODE, THE SERIES CIRCUITBEING CONNECTED IN PARALLEL WITH SAID BATTERY, AND A SERIES CIRCUITCOMPRISING SECOND DIODE MEANS AND RELATIVELY HIGH IMPEDANCE CAPACITORMEANS CONNECTED BETWEEN SAID SECOND TERMINAL AND THE GATE OF SAID SOLIDSTATE SWITCHING MEANS.